Face verification put to test: A hill-climbing attack based on the uphill-simplex algorithm

The vulnerabilities of a PCA-based face verification system against a hill-climbing attack using the uphill-simplex algorithm are studied. Experiments are carried out on the face subcorpus of the publicly available BioSecure DB, where the attack has shown a remarkable performance proving the lack of robustness of the tested system to this type of threat. Furthermore, the proposed attacking scheme is not only able to bypass the security of the recognition system, but it is also capable of reconstructing the users face image, with the privacy concerns that this entails. As a possible countermeasure to minimize the effect of the attack, score quantization is applied. This protection method is able to reduce both the success rate and the efficiency of the attack, however it does not completely succeed in preventing a possible intruder from accessing the system. The study also highlights the high adaptation capabilities of the proposed attack which had already been used to break a signature-based verification system.